v0.3.1

• Add Fallout's GenerateInstallScript target, which creates GitHub Releases Bash and Windows PowerShell installers
  from the selected PackagingTypes, exposes command help and explicit downgrade/version selection, prioritizes native
  installers over generic bundles, keeps Portable last, lists all published release versions or their release-note
  changelogs (limited to 20 releases by default), reports clean PowerShell release-resolution errors, and falls back
  when an asset or package tool is unavailable. Windows scripts can optionally try an exact WinGet package ID first and
  fall back to GitHub release assets when WinGet is unavailable or installation fails.
• Fix macOS PKG and DMG auto-updates leaving the application closed by deferring relaunch to a non-elevated helper that
  waits for the old process to exit. Set the StageKit demo's Avalonia application name so its macOS menu uses
  StageKit.
• Fix macOS DMG creation being killed with exit code 137 on GitHub-hosted runners. The image is built from the
  application bundle alone again, without the /Applications drag-and-drop symlink, because hdiutil follows that
  symlink while scanning the source tree and walks the whole host /Applications directory. PKG installers continue to
  install their application directly in /Applications. Native packages are still created before the application ZIP.
• Add opt-in LinuxAppBundleOptions.FlatpakAllowHostCommandExecution manifest configuration for applications that need
  the org.freedesktop.Flatpak host-command service.
• Stage libicu74 in Snap packages by default so self-contained .NET applications have globalization support, with a
  configurable LinuxAppBundleOptions.SnapStagePackages list for other bases and runtime dependencies.
• Add ProcessHelper host-process factories and start helpers that use flatpak-spawn --host inside Flatpak and normal
  process launching elsewhere. Updatum now installs and relaunches Flatpak updates through that bridge, using its
  host-visible application cache for downloaded bundles.
• Add HostSystem.TryFindExecutable for subprocess-free executable lookup with Windows PATHEXT support and Unix
  execute-permission validation.
• Add synchronous and asynchronous HostSystem helpers to open URLs, directories, and files with their default host
  applications, or reveal a file in Windows Explorer and macOS Finder (with containing-directory fallback on Linux).
• Add lazy BuildRuntime.Instance manifest loading and BuildRuntime.TryLoad(...) to StageKit.Runtime, using
  source-generated JSON metadata and the generic enum converter for trimming and Native AOT compatibility.